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Discussion Starter · #1 ·
Hello folks. I wonder if you guys could help me out. My 2013 Impala 3.6l has been giving me some fits for sometime now. I get the stabilitrack light and check engine light. It stared with P0300 generic misfire code. So I replaced the spark plugs with new AcDelco iridium plugs because that's what came out of it. I got it with about 75k on it and it now sits at 118k roughly. I drive it everyday about 50 miles to work and back. Anyhow, the problem persisted after the plugs, which was not terribly surprising. So I bought a couple coil packs and put them on 2 and 4. I bought 2 different brands, so I could keep track of the coils during my testing. It seemed like it fixed the problem for a few days, but then came back, so I put the exact same old coils back in their original places. Move the new coils to 6 and 1. Same results, so again moved them to 3 and 5. Same results. So without having a set cylinder code, I opted to just replace them all. Almost the same results, but now I at least get a P0302 code to be cylinder specific. So I replaced the pigtail on that coil, based off a friends suggestion who's been in auto repair longer than I've been alive. Anyhow, same results. Now during all this time, I never got the P2098 code, but I ran codes today when I got home from work and there it was. I use a Matco scanner for code reading and it has live data and I think the freeze frame data, but I have no idea how to read it. I hate to bother Larry to much, but maybe I need to get with him and have him read my scanner info. When he recommended the coil pigtail, he also talked about maybe the injector pigtail, as the 2 plug was damp when I switched it last time. At the time, I didn't think about it being fuel related, but now that I have a lean code it does make me wonder. I was googling the codes and ran across this forum, so I thought I'd give it a whirl to see what people might think or offer for recommendations. I'm pretty mechanically inclined, but chasing this new stuff is not my cup of tea. On the older stuff I'm very comfortable lol. Anyhow any thoughts or recommendations? Thank you and Happy New Year! Stay safe.
 

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2098 is a lean code.
I would take a look at the injector control pulse waveforms for all three injectors on that bank with a scope.
If you have enough channels I'd be sorely tempted to look at the ignition pulses using inductive pickups as well.

On a different tack. The timing chain and tensioner is a known problem on the LLY/LFX 3.6L that can cause multiple random misfire events. Not saying that's the problem but it's worth a diagnostic check.
 

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Discussion Starter · #3 ·
I will see if I can get Larry to do that for me. I don't have the equipment. He hooked up his scanner to it and said it was actually missing on the 2 and 4 cylinder, with 4 being worse than 2 but I don't get a 304code, so idk. We did some discussing and sense I posted, I tested the fuel pressure and vacuum. I got 48psi on the fuel, which from what I found is low. I do not see a pressure regulator but there is a pressure sensor. There is another unit that is mounted below the cylinder head, has a fuel line going in and a connector or sensor on the bottom. I assume there is 1 coming out somewhere. Not sure if thats something to do with flex fuel or something like that? I also stared the vehicle with the fuel pressure gauge on and no change, but I noted upon revving the engine a little the pressure drops and then comes back. The vacuum test also seemed kinda low at about 15in at idle in park. When you rev up the engine it goes to 20, after the initial drop. I'm not sure what the vacuum should be on this vehicle, but I assume probably more like 18 or so at idle. Any ideas?
 

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GM V6 and LS V8 intakes tend to leak. Not sure that the 3.6 is any worse or better than the V6 Buick derivatives or the 2.8L derivatives. I think they all have varying problems.
Intake gaskets are bloody easy even with the Eaton compressor on the supercharged Gen VII Impala SS & the Pontiac GTP.

Idle vacuum reading closer to 0 than it should be might point to a small intake leak. The 2-4-6 bank is the front head of the 3.6L. Cyl 2 at the harmonic balancer and 6 next to the transmission.
 
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Don't use aftermarket intake gaskets. Get genuine GM gaskets.
 

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Discussion Starter · #6 ·
Ok I appreciate the info. I'm going to do a comp check on the front 3 cyls to see if possibly a head gasket blown between cylinders and from what i've read it seems broken valve springs is somewhat common, so maybe I can tell if that might be a possibility as well. I surmise I will have to take the front valve cover off for that though. I sprayed WD40 around the intake while it was running and didn't notice any change, but its hard to get to some of it so, can't say for certain. Anyhow, just doing a little more testing before I make any changes. The odd part I guess, and I should of put this in the original thread, is that for the longest time I only got the misfire codes and no change to fuel/air or O2 codes. That O2 code is relatively recent. Its frustrating and seems potentially multiple problems, but gotta start some where.
 

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I hafta agree on that.... I always test and test again before loading the parts canon. Testing is cheap.
 

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Discussion Starter · #8 ·
Well comp test did not go very well for results
#2 only has about 40
#4 has about 90
#6 has about 120

So I need to check and see if I have a broken spring preventing a valve from closing or if I need to do a head gasket job or if the rings are maybe just worn out but I'd bank on one of the other 2 options 1st I hope. Sounds like it might be time to get a head set and take the head off and I can also do the intake gasket at the same time. Not what I wanted to see, but at least it lets me know I'm on the right track.
 

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You can build a leakdown tester or possibly rent one from O'Rileys or Autozone or ...
You can buy one for around $150 if you cant rent one from the chain stores.
It'll help you pinpoint where you're loosing compression before you begin extensive surgery.

There's a widget you can install on the radiator to test for combustion gasses being expelled from the cylinder and through the cooling system from head gaskets or cracks in the cylinders or head.
 

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Discussion Starter · #10 ·
I have to exhaust gas detector setup for the radiator. I probably need new chemical as its most likely expired. I don't believe it lasts all that long. I'm going to do some more checking on it before I tear it down. The only real scare about tearing it down is the timing chain and such. All in all with 118k miles I probably need to change all that at the same time. I just need to study up on how to set the timing and such as I doubt it's like an old small block chevy and I don't know if it requires any special tools to hold sprockets and such. So I'll study that and save up some money. I'm pretty tempted to take the valve cover off this weekend and check springs and such. Rockers are torque type from what I've read so it shouldn't be to big of deal to remove and and pressure it up with some air. I should be able to do that and then see if I get air from the #4 spark plug hole. I really hope its not a head gasket, but I'm fairly certain i have the skills and connections to do it at least.
 

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Not a bad idea to run a leakdown with the number 2 and then the number 4 pistons down with the valves closed.
The LFX 3.6L VVT engine has overhead cams. It's a bit different from the cam in block engines but not terrible. Nowhere near as bad as the BMW dumpster fire N62 V8 engines.
118K may be about time to change the 3.6L timing chain, guides, & tensioner. Plenty of howto videos on Youtube.
Once you disconnect the timing chain from the cams the head gasket should be pretty reasonably straightforward.
 

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Discussion Starter · #12 ·
So you can do the head without taking all the timing components apart? The timing setup seems complicated or at least intricate to say the least. It really looks like a real bear to do in the car, but I would imagine it can be done that way. Anyhow I planned on taking the rockers off for the leakdown testing so I know the valves would be closed. Thanks again for the tips.
 

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You should be able to do the head gasket without fouling up the timing.
I would spin the engine around til all the timing marks line up on the chain and sprockets.
 

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Discussion Starter · #14 ·
I had thought about doing that. since I have to take the timing cover off anyhow, I figure I'll give it a look over and check chain stretch. I haven't done a leak down test, but I can say that when I put my shop air supply into the cylinder it rolls the piston back down until the intake valve opens. Now granted thats 150psi roughly, so it kinda tells me that the cylinder should be sealed up for the most part. I have the intake off and the valve cover, so I know I'm at TDC. I'm going to put a regulator setup on there and reduce the pressure so I can hopefully stay on tdc and then be able to hear where the air is going to. As far as the timing, I was thinking if nothing is too stretched, I might see about cleaning it all up really good and take a paint pen to the gear and chain to mark where it all lines up. All in all it may indeed be as easy to just roll it all over until it lines up. If its stretched or guides are worn, I may get a new timing kit and install it. Its complicated, but I've found some good information on it, so I think its easily achieved as long as I'm patient and pay attention. I really wish I didn't have to take the head off, but I'll know more tomorrow when I get my air supply regulated and can tell where its going!
 
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